In the case of an air inlet unit, such as is used for example in the automobile industry or the smelting industry, it is necessary to remove contaminants in the form of particles from the air. The contaminants can occur in various forms depending upon the site where the units are situated. For example, in the smelting industry it is necessary to filter from the air dust grains which are greater in size than 10 μm, such as for example wind-borne sand or dusts, which differ greatly in density and size from organic dusts such as for example pollen.
The following methods for purifying incoming air are currently known:
In the case of a cyclone the contaminated air is directed into the inner chamber of a hollow, conical container through an inlet channel in the region of the base surface. The contaminated air flows along the conical periphery on a spiral track as far as the cone tip. The particles are carried by virtue of centrifugal force outwards to the inner side of the cone peripheral surface, decelerated by friction and collected in a catchment vessel at the cone tip. The air flow on the other hand is deflected at the cone tip and flows away along the cone axis from the cone tip in the direction of the base surface, in which there is provided an outlet orifice for purified air. The particles are thus separated by virtue of the centrifugal force. In order to achieve a high rate of separation it is necessary for the opening angle of the cone, the entry angle of the air-particle mixture and the rate of flow to correspond with each other in an optimum manner. This therefore necessitates an expensive arrangement. Moreover, the contaminated air flows along the spiral track a long way, on which the friction at the cone periphery causes pressure losses.
In the case of a gravity-fly separator the inlet air to be purified is directed into an inlet channel which is defined by two converging air guide plates. The inlet channel issues into an outlet channel for the particles. The air guide plates are provided with air channels for the purified air which lead substantially in the opposite direction to that of the flow of the incoming air-particle mixture out of the inlet channel. In this case the particles are separated by virtue of the fact that the particles are conveyed by gravitational force into the outlet channel, wherein the inlet channel which narrows in a funnel-like manner acts as a trap for the particles which are retained in this manner in the outlet channel. The gravity-fly separator can be produced and operated without great technical expenditure but the rate of separation in comparison to the cyclone is small.
The invention relates to a particle separator, in particular for an air inlet unit, comprising at least one inlet channel for a fluid flow contaminated with particles, in particular a contaminated air flow, which is defined by two opposing fluid guide surfaces, narrows in the fluid flow direction and issues into an outlet channel for particles and which is connected to at least one fluid channel for the purified fluid which leads away from the inlet channel into a region outside the inlet channel.
Moreover, the invention relates to a method for purifying a fluid flow which is contaminated with particles, in particular a contaminated air flow where the fluid flow is directed to at least one inlet channel which narrows in the original fluid flow direction and which issues into an outlet channel for particles and where the purified fluid is directed through at least one fluid channel away from the inlet channel to a discharge channel.